Vehicles such as automobiles and trucks include an internal combustion engine (ICE) that produces drive torque that accelerates the vehicle. The vehicle also includes a brake system that decelerates the vehicle. Brake systems include a brake booster that reduces braking effort by applying additional force to a master cylinder of the brake system. The brake booster uses a vacuum to apply force to the master cylinder. The brake booster vacuum is supplied by vacuum from the ICE.
Some ICE's include engine control systems that deactivate cylinders under low load situations. For example, an eight cylinder engine can be operated using four cylinders to improve fuel economy by reducing pumping losses. This process is generally referred to as displacement on demand or DOD. As used herein, activated refers to operation using all of the engine cylinders. Deactivated refers to operation using less than all of the cylinders of the engine (one or more cylinders not active).
A vehicle incorporating a DOD ICE and a brake booster requires a brake booster vacuum sensor to ensure that adequate vacuum is available for braking. If brake booster vacuum falls below a predetermined while in the deactivated mode, the ICE is transitioned to the activated mode to replenish the brake booster vacuum. A faulty brake booster sensor may prevent the ICE from transitioning to the deactivated mode and/or may cause the ICE to cycle in and out of DOD mode.